Morphological and Corrosion Characterization of Electroless Ni-P Coatings Deposited on Ductile Iron

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This work investigates the morphological and corrosion characterization of electroless Ni-P coatings deposited on ductile iron. Results show a significant increase in corrosion resistance is evidenced by the blocking effect of the coating that delimits 22 the access of the electrolyte to the ductile iron coating. The results of this paper are quite interesting, but the writing is not good and need to revise to make it more fluent.  Here are some suggestions to revise.

(1)   In the abstract: rewrite the first two sentence. “that” should be in capitals.

(2)   The authors said electroless nickel plating is of interested to improve the resistance of alloys, is there any reported results?  Please add literature results in the “introduction” part, and why did this work?

(3)   Page 2, “The surface was ground In accordance”, “In” should be lower case.

(4)   Page 3, don’t need to give the definition for the abbreviation twice, such as EIS, EN, etc.

(5)   Page 4: how did the authors get the error bar for the average thickness?

(6)   How to read Figure 7?  Lost caption

(7)   “Although the coating is highly protective and regenerates, it does not prevent the corrosion process from continuing [33].” Why?  In this case, how did you get the last conclusion?

Comments on the Quality of English Language

No

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Morphological and corrosion characterization of electroless Ni-P coatings deposited on ductile iron

 

·         Advantages of using Ni-P coatings over other conventional methods should be described to elevate this paper on its title. As sometimes increased hardness would lead to have brittleness of material under mechanical loading. Authors must specify significant advantages Ni-P coatings over ductile iron with other methods to justify and motivate this title of the paper. Like why not choosing NiPWS2 coatings? Since WS2 as a solid lubricant, that can give coatings excellent tribological properties in additional benefits to Ni-P coatings.

·         Section 2 must be elaborated more in details. Base metal and coating thickness, experimental procedure, sample diagram, (ASTM standard or?), coating methods, deposition, atomic size of coating powders, etc.,

·         Table 1 formatting error must be corrected.

·         In section 2, coating thickness was said to be 1 cm? or is it a base metal thickness? On page it was ~35 microns. Is there any bond coat in between base metal to coating substrate? How the friction between coating material and base metal is maintained.? Compatible?

·         Corrosion experiment must be also described more in details.

·         What does mean to time duration in figure 5? Exposure time?

·         More and clear descriptions on figure 5 should be provided.

·         Mechanical material property comparison of coating and base metal should be provided in a table format.

·         In Table 2, what represents the last column values?

·         Table 2 headline must be described – notations on the first title row.

·         Figure in page 9 doesn’t have any figure caption or name?

·         Figure 8 b, with Ni-P coating, with high exposure time, the localization index is higher. This means, Ni-P coating for high exposure time, was not very effective compared to substrate? This is a bit of against this paper content?!

·         Overall this paper has to be re-written for a better reading purposes.

Comments on the Quality of English Language

Morphological and corrosion characterization of electroless Ni-P coatings deposited on ductile iron

 

·         Advantages of using Ni-P coatings over other conventional methods should be described to elevate this paper on its title. As sometimes increased hardness would lead to have brittleness of material under mechanical loading. Authors must specify significant advantages Ni-P coatings over ductile iron with other methods to justify and motivate this title of the paper. Like why not choosing NiPWS2 coatings? Since WS2 as a solid lubricant, that can give coatings excellent tribological properties in additional benefits to Ni-P coatings.

·         Section 2 must be elaborated more in details. Base metal and coating thickness, experimental procedure, sample diagram, (ASTM standard or?), coating methods, deposition, atomic size of coating powders, etc.,

·         Table 1 formatting error must be corrected.

·         In section 2, coating thickness was said to be 1 cm? or is it a base metal thickness? On page it was ~35 microns. Is there any bond coat in between base metal to coating substrate? How the friction between coating material and base metal is maintained.? Compatible?

·         Corrosion experiment must be also described more in details.

·         What does mean to time duration in figure 5? Exposure time?

·         More and clear descriptions on figure 5 should be provided.

·         Mechanical material property comparison of coating and base metal should be provided in a table format.

·         In Table 2, what represents the last column values?

·         Table 2 headline must be described – notations on the first title row.

·         Figure in page 9 doesn’t have any figure caption or name?

·         Figure 8 b, with Ni-P coating, with high exposure time, the localization index is higher. This means, Ni-P coating for high exposure time, was not very effective compared to substrate? This is a bit of against this paper content?!

·         Overall this paper has to be re-written for a better reading purposes.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, the corrosion behaviour of uncoated ductile steel was compared with that of the same steel with a Ni-P coating, in a 0.1 M NaCl solution, by electrochemical impedance spectroscopy and electrochemical noise. The Ni-P coating was applied by electroless nickel plating and characterized by XRD, SEM/EDS and Vickers microhardness.

The Introduction and the Abstract clearly outline the topic but are not clear concerning the medium used in the study (0.1 M NaCl). In addition, the experimental part is not sufficiently extensive to follow all procedures, and the presentation of the results could also be improved following the comments below:

1.      SEM/EDS experimental conditions and sample preparations should be described.

2.      Metallographic preparation for coating cross-section measurements should be described.

3.      The software used for coating thickness measurements, EIS fittings, and for electrochemical noise analysis should be identified.

4.      The working electrode should be described in more detail (how was crevice corrosion prevented?)

5.      SEM and EDS results (Fig. 2) should be described in more detail to support the conclusion that “the coating exhibits excellent adhesion to the substrate, displaying high compactness and a defects-free surface devoid of any observable imperfections such as pores or discontinuities” (section 3.1. line 133-135).

6.      ICSD references used to preset XRD results should be better discussed and framed within the scope of the work.

7.      Some small details:

a.      Section 1. Line 55. “austempering”, not “Austempering”

b.      Section 2. Line 82. “in accordance”, not “In accordance”

c.       Section 2. Line 115. “were”, not “was”

d.      Section 3.2. Line 212. PO₄ ^3- , not PO4 ^3-

e.      Section 4. Line 290. delete “5. Patents”

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All my questions have been solved. 

Reviewer 2 Report

Comments and Suggestions for Authors

accepted for publication

Comments on the Quality of English Language

accepted for publication after review comments

Reviewer 3 Report

Comments and Suggestions for Authors

All comments have been adequately considered in the current writing of the manuscript